Small and wide angle X-ray studies of impregnated activated carbons

Small angle X-ray scattering (SAXS) and powder X-ray diffraction (XRD) measurements were made on CuO-impregnated activated carbons, prepared with and without an HNO3 co-impregnant, in order to determine the effect of impregnant loading and HNO3 content on impregnant distribution. A comprehensive matrix of 30 CuO-impregnated samples with five HNO3 concentrations and six impregnant loadings was prepared and studied. As a highlight, in Cu-based samples prepared with no HNO3, relatively small particle size CuO impregnant (approximately 3 nm) was observed at low impregnant loading and additional CuO appeared in large particles (>10 nm diameter) in meso and macropores as the impregnant loading increased. By contrast, when 4 M HNO3 was present during the impregnation, the largest impregnant particles found were less than 4 nm. Results from SAXS data were shown to be in good agreement with XRD and data obtained from nitrogen gas adsorption isotherms. The combination of SAXS and XRD is shown to be a powerful combination in elucidating the nanostructure of impregnated activated carbons.